Laboratoire des Interactions Plantes-Microorganismes, CNRS UMR2594, Castanet-Tolosan, France.
PLoS One. 2013 May 23;8(5):e61075. doi: 10.1371/journal.pone.0061075. Print 2013.
Life-history traits controlling the duration and timing of developmental phases in the life cycle jointly determine fitness. Therefore, life-history traits studied in isolation provide an incomplete view on the relevance of life-cycle variation for adaptation. In this study, we examine genetic variation in traits covering the major life history events of the annual species Arabidopsis thaliana: seed dormancy, vegetative growth rate and flowering time. In a sample of 112 genotypes collected throughout the European range of the species, both seed dormancy and flowering time follow a latitudinal gradient independent of the major population structure gradient. This finding confirms previous studies reporting the adaptive evolution of these two traits. Here, however, we further analyze patterns of co-variation among traits. We observe that co-variation between primary dormancy, vegetative growth rate and flowering time also follows a latitudinal cline. At higher latitudes, vegetative growth rate is positively correlated with primary dormancy and negatively with flowering time. In the South, this trend disappears. Patterns of trait co-variation change, presumably because major environmental gradients shift with latitude. This pattern appears unrelated to population structure, suggesting that changes in the coordinated evolution of major life history traits is adaptive. Our data suggest that A. thaliana provides a good model for the evolution of trade-offs and their genetic basis.
生活史特征控制着生命周期中各个发育阶段的持续时间和时间，共同决定了适合度。因此，孤立地研究生活史特征提供了对生命周期变化对适应的相关性的不完整认识。在这项研究中，我们研究了覆盖一年生植物拟南芥主要生活史事件的特征的遗传变异：种子休眠、营养生长速度和开花时间。在从物种的整个欧洲范围内收集的 112 个基因型样本中，种子休眠和开花时间都遵循与主要种群结构梯度无关的纬度梯度。这一发现证实了先前报道这两个特征适应性进化的研究。然而，在这里，我们进一步分析了特征之间的协同变化模式。我们观察到，主要休眠、营养生长速度和开花时间之间的协同变化也遵循纬度梯度。在高纬度地区，营养生长速度与主要休眠呈正相关，与开花时间呈负相关。在南方，这种趋势消失了。特征协同变化的模式发生变化，可能是因为主要环境梯度随纬度而变化。这种模式似乎与种群结构无关，表明主要生活史特征协调进化的变化是适应性的。我们的数据表明，拟南芥为权衡及其遗传基础的进化提供了一个很好的模型。
